\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{circuitikz}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\ctikzset{bipoles/length=1cm}
\begin{document}
\small
\begin{circuitikz}[>=latex, scale=0.8,european]
  % \useasboundingbox(0.9,0)rectangle(5.1,5);
  \draw(0,0)--(5,0) to [R=$R$](5,3) to  [cute open switch] (2,3)--(0,3) to[battery2] (0,0);
  \draw (2,0) to [rmeter, t=V, *-*] (2,3);    
  \node at (7/2,3)[above] {$K$};
\end{circuitikz}
\end{document}